1. Field of the Invention
The present invention relates to an antenna amplifier, a receiving system, an operating method, and use of a receiving system in a motor vehicle.
2. Description of the Background Art
European Pat. Appl. No. EP 1035659 A1 discloses a radio receiver with a multi-antenna stage and a receiver stage, whereby the receiver stage has a switching unit for switching between receiving of frequency-modulated radio waves (FM operation) and amplitude-modulated radio waves (AM operation), as well as at least one intermediate frequency amplifier. An input of the receiver stage and an output of the intermediate frequency amplifier are connected at least indirectly via a connecting line with the multi-antenna stage for receiving of radio signals from the multi-antenna stage or for transmitting of amplified intermediate frequency signals to the multi-antenna stage.
The multi-antenna stage has an evaluation circuit for selecting a receive antenna as a function of signals transmitted from the receiver stage. The radio receiver has a decoupling unit between the output of the intermediate frequency amplifier and the connecting line, whose decoupling effect can be activated (decoupling stage) or deactivated (transmission stage) by switching between the AM operation and FM operation, or vice versa.